//乘法
function _mul(arg1, arg2) {
  if (isNaN(arg1)) {
    arg1 = 0;
  }
  if (isNaN(arg2)) {
    arg2 = 0;
  }
  arg1 = Number(arg1);
  arg2 = Number(arg2);

  var m = 0,
    s1 = arg1.toString(),
    s2 = arg2.toString();
  try {
    m += s1.split(".")[1].length;
  } catch (e) { }
  try {
    m += s2.split(".")[1].length;
  } catch (e) { }
  return Number(s1.replace(".", "")) * Number(s2.replace(".", "")) / Math.pow(10, m);
}
//加法
function _add(arg1, arg2) {
  if (isNaN(arg1)) {
    arg1 = 0;
  }
  if (isNaN(arg2)) {
    arg2 = 0;
  }
  arg1 = Number(arg1);
  arg2 = Number(arg2);
  var r1, r2, m, c;
  try {
    r1 = arg1.toString().split(".")[1].length;
  } catch (e) {
    r1 = 0;
  }
  try {
    r2 = arg2.toString().split(".")[1].length;
  } catch (e) {
    r2 = 0;
  }
  c = Math.abs(r1 - r2);
  m = Math.pow(10, Math.max(r1, r2));
  if (c > 0) {
    var cm = Math.pow(10, c);
    if (r1 > r2) {
      arg1 = Number(arg1.toString().replace(".", ""));
      arg2 = Number(arg2.toString().replace(".", "")) * cm;
    } else {
      arg1 = Number(arg1.toString().replace(".", "")) * cm;
      arg2 = Number(arg2.toString().replace(".", ""));
    }
  } else {
    arg1 = Number(arg1.toString().replace(".", ""));
    arg2 = Number(arg2.toString().replace(".", ""));
  }
  return (arg1 + arg2) / m;

}
//减法
function _minus(arg1, arg2) {
  if (isNaN(arg1)) {
    arg1 = 0;
  }
  if (isNaN(arg2)) {
    arg2 = 0;
  }
  arg1 = Number(arg1);
  arg2 = Number(arg2);

  var r1, r2, m, n;
  try {
    r1 = arg1.toString().split(".")[1].length;
  } catch (e) {
    r1 = 0;
  }
  try {
    r2 = arg2.toString().split(".")[1].length;
  } catch (e) {
    r2 = 0;
  }
  m = Math.pow(10, Math.max(r1, r2)); //last modify by deeka //动态控制精度长度
  n = (r1 >= r2) ? r1 : r2;
  return ((arg1 * m - arg2 * m) / m).toFixed(n);

}

module.exports = {
  _add: _add,
  _mul: _mul,
  _minus: _minus
}